JP5285309B2 - Exhaust gas purification device - Google Patents

Description

  The present invention relates to an apparatus for purifying exhaust gas of an internal combustion engine such as a diesel engine, a gas engine, a gasoline engine or a gas turbine engine, or a combustion device such as an incinerator or a boiler, and performs a normal operation particularly in an excess air state. The present invention relates to an exhaust gas purification device that is connected to an exhaust passage of an internal combustion engine or the like and removes nitrogen oxides.

  Exhaust gas discharged from an internal combustion engine or the like contains nitrogen oxides, carbon monoxide, hydrocarbons, and the like as harmful components. Various devices have been developed in the past for removing these substances from the exhaust gas and purifying the exhaust gas.

  The present applicant has developed an exhaust gas purification device and has already filed an application (Patent Document 1). FIG. 4 shows the exhaust gas purifying device described in FIG. As shown in FIG. 4, the conventional exhaust gas purification apparatus by the present applicant has a nitrogen oxide adsorbent 204 and a first oxide gas in each of a plurality of branch exhaust passages 202 a and 202 b connected to an internal combustion engine or the like. A combustion device (adsorbing substance desorbing means) 203 and a second combustion device 205 are provided. Exhaust gas from an internal combustion engine or the like is supplied only to a part of the branch exhaust passages 202a (or 202b) and is not supplied to the other branch exhaust passages 202b (or 202a). In the branch exhaust passage 202a to which exhaust gas is supplied, nitrogen oxides are adsorbed and removed by the nitrogen oxide adsorbent 204, and carbon monoxide and carbonization are performed by the oxidation catalyst of the nitrogen oxide adsorbent 204. Hydrogen is oxidized to carbon dioxide and water. On the other hand, in the branch exhaust passage 202b in which the supply of exhaust gas is cut off, the first combustion device 203 generates a reducing atmosphere so that it is desorbed from the nitrogen oxide adsorbent 204 and is desorbed. The object is reduced to nitrogen by the second combustion device 205. That is, in some branch exhaust passages 202a, normal operation is performed in which nitrogen oxides are adsorbed by the nitrogen oxide adsorbent 204, and at the same time, nitrogen oxides are desorbed from the adsorbent 204 in other branch exhaust passages 202b. The regeneration operation is performed, and the adsorption capability of the nitrogen oxide adsorbent 204 is maintained.

The exhaust gas purification device shown in FIG. 4 is a purification device that does not use a three-way catalyst, ammonia, urea, or the like. A three-way catalyst is a catalyst that can simultaneously decompose nitrogen oxides, carbon monoxide, and hydrocarbons, but does not work effectively in an excess air environment. A purification apparatus using ammonia or the like has many problems because the apparatus itself is very complicated and expensive, and maintenance costs for ammonia as a reducing agent and a supply system for ammonia and the like are also required. The exhaust gas purification device shown in FIG. 4 solves the above problems. The exhaust gas purification apparatus shown in FIG. 4 removes and purifies harmful components (nitrogen oxides, carbon monoxide, hydrocarbons) from exhaust gas discharged from an internal combustion engine or the like operated under an excess air condition. Moreover, it can be maintained without reducing its purification ability.
JP 2006-272115 A

  In the exhaust gas purification device shown in FIG. 4, the reducing atmosphere is supplied to the nitrogen oxide adsorbent 204 by causing the first combustion device (adsorbed substance desorbing means) 203 to generate a combustion reaction under excessive fuel conditions. . Although it is necessary to continuously supply the reducing atmosphere until the regeneration operation is completed, the normal operation cannot be performed during the regeneration operation in the same branch exhaust passage. An increase in the execution time of the regeneration operation causes a reduction in processing efficiency of the exhaust gas purification device. On the other hand, in order to shorten the implementation time of the regeneration operation, it is conceivable to increase the flow rate of the reducing atmosphere. However, when the flow rate of the reducing atmosphere is increased, the energy consumption (reducing agent consumption) required to generate the reducing atmosphere increases. The energy consumption corresponds to the amount of fuel consumed when the reducing atmosphere generating means is a combustion device (in the case of the exhaust gas purification device of FIG. 4). That is, if it is attempted to increase the amount of nitrogen oxide desorbed from the nitrogen oxide adsorbent, the energy consumption required for desorption or the time required for desorption (desorption time) will increase.

  The present invention provides an exhaust gas purifying apparatus configured to desorb nitrogen oxide from a nitrogen oxide adsorbent by supplying a reducing atmosphere without increasing energy consumption required for desorption and time required for desorption. An object is to efficiently increase the amount of nitrogen oxide desorbed.

A control method for an exhaust gas purifying apparatus according to the present invention includes: a plurality of branch exhaust passages connected to an engine side exhaust passage of an internal combustion engine or a combustion device; and an exhaust inlet of each branch exhaust passage being opened or closed, Exhaust gas shutoff means for switching inflow and shutoff of exhaust gas from the engine side exhaust passage to each branch exhaust passage, and provided in each branch exhaust passage, temporarily adsorbing nitrogen oxides in an excess air atmosphere, A nitrogen oxide adsorbing material that desorbs the adsorbed nitrogen oxide in a temperature rising or reducing atmosphere, and an air supply means, a fuel supply, arranged in each branch exhaust passage upstream of the nitrogen oxide adsorbing material And a first combustion device configured to supply and combust a first mixed gas in which fuel and air are mixed, and disposed in each branch exhaust passage on the exhaust downstream side of the nitrogen oxide adsorbent Air And a second combustion device comprising a supply means, a fuel supply means, and an ignition means, wherein there is a normal operation and a regeneration operation for each branch exhaust passage, The normal operation is an operation in which exhaust gas flows into the branch exhaust passage where the normal operation is performed by switching the exhaust gas blocking means, and the regeneration operation is the regeneration by switching the exhaust gas blocking means. The operation in which the first combustion device and the second combustion device are operated in a state in which the exhaust gas is prevented from flowing into the branch exhaust passage where the operation is performed , and the regeneration operation is performed in order. A regeneration operation, a first main regeneration operation, a second main regeneration operation, and a post-regeneration operation . In the first main regeneration operation and the second main regeneration operation , the excess air ratio λ of the first mixed gas is , Λ Is controlled to a range of 1.0, in the front regeneration operation and the post-regeneration operation, the excess air ratio of the first gas mixture lambda is, is controlled in the range of lambda> 1.0, the first The flow rate of the first mixed gas decreases in the order of main regeneration operation, pre-regeneration operation, post-regeneration operation, and second main regeneration operation .

In the previous SL first main regeneration operation and the second main regeneration operation, the excess air ratio of the first mixed gas lambda is controlled to 0.6 <lambda <1.0 range.

According to the onset bright, as steps in the regeneration operation progresses, by decreasing the flow rate of the first gas mixture, without increasing the time required for the energy consumption and elimination, efficient, nitrogen oxides removal The amount of separation can be increased. Further, since the temperature is raised in the initial stage of the main regeneration operation, the start of desorption can be accelerated. In addition, the amount of particulate matter captured by the nitrogen oxide adsorbing material can be reduced. Further, the temperature of the nitrogen oxide adsorbing material can be raised prior to the main regeneration operation, and the efficiency of the main regeneration operation can be improved. Moreover, the reducing agent adhering to the nitrogen oxide adsorbing material can be removed, and the amount of reducing agent discharged outside the apparatus when normal operation is performed can be reduced. In addition, the amount of particulate matter captured by the nitrogen oxide adsorbing material can be reduced.

Furthermore, according to the present invention , nitrogen oxide can be effectively desorbed from the nitrogen oxide adsorbent.

[Exhaust gas purification apparatus according to this embodiment]
An exhaust gas purification apparatus 1 according to the present embodiment will be described with reference to FIG. The exhaust gas purification device 1 is a device connected to an engine side exhaust passage 100 of an internal combustion engine or combustion equipment.

  An internal combustion engine or a combustion device burns a mixed gas of air and fuel to generate exhaust gas. The exhaust gas contains nitrogen oxides (N0x), carbon monoxide (C0), hydrocarbons (HC), and the like as unburned substances. The engine side exhaust passage 100 is an exhaust passage provided in the internal combustion engine or the combustion equipment. Exhaust gas generated by the internal combustion engine or the combustion equipment is discharged from the engine side exhaust passage 100.

  FIG. 1 shows an engine-side exhaust passage 100, a plurality (two in this embodiment) of branched exhaust passages 2 and 3, and a merged exhaust passage 110 as exhaust gas passages. The branch exhaust passages 2 and 3 are exhaust passages provided in the exhaust gas purification device 1. The exhaust outlet 100 b of the engine side exhaust passage 100 is connected to the exhaust inlets 2 a and 3 a of the branch exhaust passages 2 and 3. The exhaust outlets 2b and 3b of the branch exhaust passages 2 and 3 are connected to the merged exhaust passage 110a. These exhaust passages 100, 2, 3 and 110 are passages cut off from outside air, and are constituted by pipes, for example. The merged exhaust passage 110 may be an exhaust passage provided in the exhaust gas purification device 1 or an exhaust passage of an internal combustion engine or a combustion device.

  F indicates the direction in which the gas (exhaust gas) flowing through the branch exhaust passages 2 and 3 flows. The side indicated by the arrow in the direction F is the exhaust downstream side, and the opposite side indicated by the arrow in the direction F is the exhaust upstream side.

  The exhaust gas from the engine side exhaust passage 100 flows from the exhaust inlet 2a to the exhaust outlet 2b in the branch exhaust passage 2, and flows from the exhaust inlet 3a to the exhaust outlet 3b in the branch exhaust passage 3.

  The exhaust gas purification device 1 includes a control device (electronic control unit) 10. The control device 10 controls each device (described later) provided in the exhaust gas purification device 1.

  The exhaust gas purification device 1 closes the exhaust inlets 2a and 3a of the branch exhaust passages 2 and 3 so that the exhaust gas flowing from the engine side exhaust passage 100 to the branch exhaust passages 2 and 3 can be blocked. A blocking means is provided.

  As the exhaust gas blocking means, specifically, a gas cutoff valve 4 is provided at the junction of the engine side exhaust passage 100 and the branch exhaust passages 2 and 3. The shutoff valve 4 shuts off or allows the inflow of exhaust gas from the exhaust outlet 100b of the engine side exhaust passage 100 to the exhaust inlets 2a and 3a of the branch exhaust passages 2 and 3. Switching between shut-off and allowance by the shut-off valve 4 is performed under the control of the control device 10. Note that the exhaust gas blocking means may be a group of switching valves provided for each of the branch exhaust passages 2 and 3. In this case, each switching valve is provided at the exhaust inlet 2 a of the branch exhaust passage 2 and the exhaust inlet 3 a of the branch exhaust passage 3, respectively.

  The exhaust gas purification device 1 includes a nitrogen oxide adsorbent 5, a first combustion device 6, a second combustion device 7, and an auxiliary air supply means 15 in the branch exhaust passages 2 and 3, respectively. . In each branch exhaust passage 2, 3, the first combustion device 6, the nitrogen oxide adsorbing material 5, the second combustion device 7, and the auxiliary air supply means 15 are sequentially arranged toward the exhaust downstream side.

  The nitrogen oxide adsorbing material 5 is a material that temporarily adsorbs nitrogen oxide in an excess air atmosphere and desorbs the adsorbed nitrogen oxide in a reducing atmosphere. Further, when the nitrogen oxide adsorbing material 5 is placed in a temperature rising atmosphere in addition to the reducing atmosphere, the nitrogen oxide is more effectively desorbed.

  Here, the excess air refers to a state where the excess air ratio (a value obtained by dividing the air-fuel ratio of the supplied mixed gas by the ideal air-fuel ratio) is greater than 1 in the mixed gas of air (oxygen) and fuel. A state where the excess air ratio is smaller than 1 is a state where the fuel is excessive. The reducing atmosphere refers to a gas in which the reducing agent is excessive and oxygen is insufficient when combustion (oxidation and reduction reaction) occurs.

  The nitrogen oxide adsorbing material 5 also has a catalyst component having an oxidizing action.

  The first combustion device 6 includes air supply means, fuel supply means, and ignition means. And the 1st combustion apparatus 6 supplies and burns the 1st mixed gas with which fuel and air were mixed. The first combustion device 6 generates a reducing atmosphere containing unburned substances (carbon monoxide and hydrocarbons) as a reducing agent by generating a combustion reaction under an excess fuel condition, and generates heat by the heat of the combustion reaction. It is possible to generate a temperature rising atmosphere.

  The air supply means of the first combustion device 6 includes an air supply device 11, an air metering device 12, and an air nozzle 61. The air supply device 11 takes in outside air and supplies it to the air metering device 12. The air metering device 12 supplies the supplied air (outside air) to the air nozzle 61 after adjusting the air amount. The air nozzle 61 is a nozzle that opens to the first combustion region A1 in the branch exhaust passages 2 and 3. The air supplied to the air nozzle 61 is injected into the branch exhaust passages 2 and 3. Here, the control device 10 controls the air metering device 12 to adjust the amount of air supplied to the air nozzle 61.

  The fuel supply means of the first combustion device 6 includes a control device 10, a fuel tank 13, a fuel metering device 14, and a fuel nozzle 62. Fuel is stored in the fuel tank 13. The fuel metering device 14 supplies the fuel supplied from the fuel tank 13 to the fuel nozzle 62 after adjusting the amount of fuel. The fuel nozzle 62 is a nozzle that opens to the first combustion region A1 in the branch exhaust passages 2 and 3. The first combustion region A1 is located on the exhaust upstream side of the nitrogen oxide adsorbent 5. The fuel supplied to the fuel nozzle 62 is injected into the branch exhaust passages 2 and 3. In addition, the control device 10 controls the fuel metering device 14 to adjust the amount of fuel supplied to the fuel nozzle 62.

  The ignition means of the first combustion device 6 is a spark plug 63. The spark plug 63 is a device that performs ignition in the branch exhaust passages 2 and 3. Here, the mixed gas is generated in the first combustion region A1 in the branch exhaust passages 2 and 3 by the air injected from the air nozzle 61 and the fuel injected from the fuel nozzle 62. The spark plug 63 ignites and burns this mixed gas.

  The first combustion device 6 generates a temperature rising and reducing atmosphere on the exhaust downstream side of the first combustion device 6. The temperature rising atmosphere is generated by the heat of combustion of the mixed gas. The reducing atmosphere is generated when unburned substances (carbon monoxide, hydrocarbons) are generated by the combustion of the mixed gas. Therefore, the first combustion device 6 has air supply means and is means for raising the temperature of the air supplied from the air supply means to a reducing atmosphere.

  The position of the first combustion device 6 indicates the position of the air nozzle 61, the combustion nozzle 62, and the spark plug 63. The first combustion device 6 is disposed upstream of the nitrogen oxide adsorbent 5 in each branch exhaust passage 2, 3.

  The second combustion device 7 includes air supply means, fuel supply means, and ignition means. The second combustion device 7 reduces the nitrogen oxides to nitrogen by generating a combustion reaction under excessive fuel conditions.

  The air supply means of the second combustion device 7 is the same as the air supply means of the first combustion device 6. The air supply means of the second combustion device 7 includes an air supply device 11, an air metering device 12, and an air nozzle 71. That is, the air nozzle 61 of the air supply means of the first combustion device 6 is replaced with the air nozzle 71 in the air supply means of the second combustion device 7. The air nozzle 71 is open to the second combustion region A2 in the branch exhaust passages 2 and 3.

  The fuel supply means of the second combustion device 7 is the same as the fuel supply means of the first combustion device 6. The fuel supply means of the second combustion device 7 includes a fuel tank 13, a fuel metering device 14, and a fuel nozzle 72. That is, the fuel nozzle 62 of the air supply means of the first combustion device 6 is replaced with the fuel nozzle 72 in the fuel supply means of the second combustion device 7. The fuel nozzle 62 opens to the second combustion region A2 in the branch exhaust passages 2 and 3.

  The ignition means of the second combustion device 7 is the same as the ignition means of the first combustion device 6. The ignition means of the second combustion device 7 is an ignition plug 73, which is an device that performs ignition in the second combustion region A <b> 2 in the branch exhaust passages 2 and 3.

  The position of the second combustion device 7 indicates the position of the air nozzle 71, the combustion nozzle 72, and the spark plug 73. The second combustion device 7 is disposed downstream of the nitrogen oxide adsorbing material 5 in the branch exhaust passages 2 and 3.

  The auxiliary air supply means 15 is the same as the air supply means of the first combustion device 6 and the second combustion device 7. The auxiliary air supply means 15 includes an air supply device 11, an air metering device 12, and an air nozzle 151. The air nozzle 151 corresponds to the air nozzle 61 of the first combustion device 6 and the air nozzle 71 of the second combustion device 7. Note that the air nozzle 151 opens to the third combustion region A3 in the branch exhaust passages 2 and 3.

  The position of the auxiliary air supply means 15 indicates the position of the air nozzle 151. The auxiliary air supply means 15 is disposed in each branch exhaust passage 2, 3 on the exhaust downstream side of the air supply means of the second combustion device 7.

[Control method of this embodiment]
Next, a control method of the exhaust gas purification device 1 of the present embodiment will be described. The control method of the present embodiment is a method of performing the control described below in the exhaust gas purification device 1 described above.

  The operations performed in the branch exhaust passages 2 and 3 include a normal operation and a regeneration operation. The control device 10 controls the operation.

  The normal operation is an operation in which the exhaust gas is caused to flow into the branch exhaust passages 2 and 3 in which the normal operation is performed by switching the cutoff valve 4. During normal operation, nitrogen oxide is adsorbed on the nitrogen oxide adsorbing material 5.

  The regeneration operation is an operation in which the first combustion device 6 and the second combustion device 7 are operated in a state in which the exhaust gas is prevented from flowing into the branch exhaust passages 2 and 3 where the regeneration operation is performed by switching the shut-off valve 4. It is. In the regeneration operation, nitrogen oxide is desorbed from the nitrogen oxide adsorbent 5 to regenerate the adsorption capacity of the nitrogen oxide adsorbent 5 (main regeneration operation: described later), and the nitrogen oxide adsorbent 5 is captured. And a reductant (unburned material) and an operation for removing particulate matter by oxidation (pre-regeneration operation, post-regeneration operation: described later).

  Here, in normal operation, particulate matter contained in the exhaust gas is captured by the nitrogen oxide adsorbent 5. The particulate matter is fine particles composed of carbon, hydrocarbons, sulfates and the like. An increase in the amount of trapped particulate matter also reduces the adsorption capacity of the nitrogen oxide adsorbent 5. For this reason, in the regeneration operation, the particulate matter captured by the nitrogen oxide adsorbing material 5 is also removed.

  FIG. 2 shows an example of a time table for normal operation and regeneration operation in each of the branch exhaust passages 2 and 3. In each branch exhaust passage 2, 3, the normal operation and the regeneration operation are periodically repeated. The continuous execution time of the normal operation is the normal operation time WN, and the continuous execution time of the regeneration operation is the regeneration operation time WR.

  Switching between normal operation and regeneration operation is performed when the continuous execution time of the operation has passed a predetermined time. Or the sensor which detects the adsorption amount of the nitrogen oxide in the nitrogen oxide adsorbent 5 may be provided, and the normal operation and the regeneration operation may be switched based on the detected value of the adsorption amount.

  The normal operation is always performed in any one of the branch exhaust passages 2 and 3 so that the exhaust gas discharge is not interrupted. This means the following. Each of the branch exhaust passages 2 and 3 repeats the normal operation and the regeneration operation, but the regeneration operation is not simultaneously executed in all the branch exhaust passages 2 and 3. On the other hand, the normal operation may be simultaneously executed in all the branch exhaust passages 2 and 3. In the example shown in FIG. 2, the normal operation partially overlaps on the time axis in both of the branch exhaust passages 2 and 3. On the other hand, the regeneration operation is not executed simultaneously in both the branch exhaust passages 2 and 3.

  The control device 10 starts the regeneration operation in the branch exhaust passage 2 and starts the normal operation in the branch exhaust passage 3 at the operation start time T0 (when the operation of the exhaust gas purification device 1 is started). That is, the control device 10 controls the shutoff valve 4 to shut off the engine side exhaust passage 100 and the branch exhaust passage 2 and to connect the engine side exhaust passage 100 and the branch exhaust passage 3. For this reason, the exhaust gas flows into the branch exhaust passage 3. In addition, the control device 10 operates the first combustion device 6, the second combustion device 7, and the auxiliary air supply means 15 in the branch exhaust passage 2 to be regenerated.

  In the branch exhaust passage 2, the regeneration operation is executed from the operation start time T0 to the time T1, the normal operation is executed from the time T1 to the time T4, and the regeneration operation is executed from the time T4 to the time T5. The time width from time T0 to time T1 and the time width from time T4 to time T6 are regeneration operation times WR. Further, the time width from time T1 to time T4 is the normal operation time WN.

  In the branch exhaust passage 3, the normal operation is executed from the operation start time T0 to the time T2, the regeneration operation is executed from the time T2 to the time T3, and the normal operation is executed from the time T3 to the time T6. The time width from time T3 to time T6 is the normal operation time WN. The time width from time T2 to time T3 is the regeneration operation time WR.

  As shown in FIG. 3, the regeneration operation specifically includes a pre-regeneration operation, a main regeneration operation, and a post-regeneration operation. The main regeneration operation is an operation in which nitrogen oxide is desorbed from the nitrogen oxide adsorbent 5 and reduced. The pre-regeneration operation is an operation that oxidizes and removes the reducing agent (unburned material) and particulate matter captured by the nitrogen oxide adsorbing material 5. The post-regeneration operation is an operation for oxidizing and removing the particulate matter and unburned substances (hydrocarbon and carbon monoxide) captured by the nitrogen oxide adsorbing material 5. Note that the regeneration operation may not include one or both of the pre-regeneration operation and the post-regeneration operation.

  The main regeneration operation consists of at least two stages of operation. In the present embodiment, the main regeneration operation consists of a two-stage operation, and consists of a first main regeneration operation and a second main regeneration operation.

  In the time series, in the regeneration operation, the operation is performed in the order of the pre-regeneration operation, the first main regeneration operation, the second main regeneration operation, and the post-regeneration operation.

  The first combustion device 6 operates in each of the pre-regeneration operation, the main regeneration operation, and the post-regeneration operation. By the operation of the first combustion device 6, after the first mixed gas in which the fuel and the air are mixed is generated in the first combustion region A1, the first mixed gas is burned. A first post-combustion gas is generated by the combustion of the first mixed gas.

  In the pre-regeneration operation, the operation of the first combustion device 6 is controlled as follows. The excess air ratio λ of the first mixed gas is controlled in the range of λ> 1.0. The flow rate (air supply amount per unit time) of the first mixed gas is controlled to the flow rate V3. The execution time of the pre-regeneration operation is controlled to the time width BR.

  In the first main regeneration operation, the operation of the first combustion device 6 is controlled as follows. The excess air ratio λ of the first mixed gas is controlled in the range of 0.6 <λ <1.0. The flow rate of the first mixed gas (air supply amount per unit time) is controlled to the flow rate V4. The execution time of the pre-regeneration operation is controlled to the time width MR1.

  In the second main regeneration operation, the operation of the first combustion device 6 is controlled as follows. The excess air ratio λ of the first mixed gas is controlled in the range of 0.6 <λ <1.0. The flow rate (air supply amount per unit time) of the first mixed gas is controlled to the flow rate V1. The execution time of the pre-regeneration operation is controlled to the time width MR2.

  Here, the flow rate V4 of the first main regeneration operation is larger than the flow rate V1 of the second main regeneration operation. That is, as the stage in the main regeneration operation proceeds, the flow rate of the first mixed gas is decreased. The execution time (time width MR1) of the first main regeneration operation is shorter than the execution time (time width MR2) of the second main regeneration operation.

  In the post-regeneration operation, the operation of the first combustion device 6 is controlled as follows. The excess air ratio λ of the first combustion region A1 is controlled in the range of λ> 1.0. The gas flow rate (air supply amount per unit time) supplied to the first combustion region A1 is controlled to the flow rate V2. The execution time of the post-regeneration operation is controlled to the time width AR.

[Operation of this embodiment]
Next, the operation of the exhaust gas purification apparatus 1 according to the control method of the present embodiment will be described.

  When the operation of the internal combustion engine or the like connected to the exhaust gas purification device 1 is started, the control device 10 starts the operation of the exhaust gas purification device 1 accordingly. The control device 10 performs a normal operation or a regeneration operation in each of the branch exhaust passages 2 and 3 in accordance with the operation of the exhaust gas purification device 1.

  The execution status of normal operation will be described. Exhaust gas enters the branch exhaust passage 2 (or 3) that is the target of normal operation. When the exhaust gas passes through the nitrogen oxide adsorbing material 5, nitrogen oxide contained in the exhaust gas is adsorbed by the nitrogen oxide adsorbing material 5. Then, nitrogen oxides are removed from the exhaust gas. Further, since the nitrogen oxide adsorbing material 5 has an oxidation catalyst component, unburned substances (carbon monoxide and hydrocarbons) contained in the exhaust gas are oxidized. Carbon monoxide and hydrocarbons are oxidized and detoxified by carbon dioxide and water. Then, carbon monoxide and hydrocarbons are removed from the exhaust gas.

  The exhaust gas that has passed through the nitrogen oxide adsorbing material 5 is released into the atmosphere via the merged exhaust passage 110.

  If the execution of the normal operation is continued, the amount of nitrogen oxide adsorbed on the nitrogen oxide adsorbent 5 increases, and the adsorption capacity of the nitrogen oxide adsorbent 5 decreases. In order to regenerate the adsorption capacity of the nitrogen oxide adsorbing material 5, it is necessary to desorb nitrogen oxide from the nitrogen oxide adsorbing material 5. The adsorption capacity of the nitrogen oxide adsorbing material 5 is regenerated by the regeneration operation.

  When the execution time of the normal operation has passed the normal operation time WN, the control device 10 ends the normal operation and starts the regeneration operation in the branch exhaust passage 2 (or 3) where the normal operation has been executed.

  The execution status of the regeneration operation will be described. The entrance of exhaust gas is blocked into the branch exhaust passage 2 (or 3) to be regenerated. In the regeneration operation, the control device 10 sequentially executes a pre-regeneration operation, a main regeneration operation, and a post-regeneration operation. The control device 10 operates the first combustion device 6 in any of the pre-regeneration operation, the main regeneration operation, and the post-regeneration operation. And the 1st mixed gas (mixed gas of fuel and air) which the 1st combustion device 6 generated is burned, and the 1st after-combustion gas is generated. Here, when air is injected from the air nozzle 61, a gas flow toward the exhaust downstream side is formed in the branch exhaust passage 2 (or 3). For this reason, the first post-combustion gas is sent to the exhaust downstream side (nitrogen oxide adsorbent 5 side).

  In the pre-regeneration operation, the control device 10 operates the first combustion device 6 under an excess air condition. For this reason, when the first post-combustion gas passes through the nitrogen oxide adsorbent 5, the particulate matter trapped by the nitrogen oxide adsorbent 5 is oxidized and removed. Further, the temperature of the nitrogen oxide adsorbent 5 is raised by the heat of the first burned gas. For this reason, in the main regeneration operation following the pre-regeneration operation, the nitrogen oxide adsorbing material 5 is already heated.

  The first post-combustion gas that has passed through the nitrogen oxide adsorbing material 5 is sent to the exhaust downstream side, and is released into the atmosphere via the merged exhaust passage 110.

  In the main regeneration operation (the first main regeneration operation and the second main regeneration operation), the control device 10 operates the first combustion device 6 under an excess fuel condition. For this reason, the first post-combustion gas contains a large amount of unburned carbon monoxide and hydrocarbons. Carbon monoxide and hydrocarbons act as nitrogen oxide reducing agents. For this reason, when the first burned gas passes through the nitrogen oxide adsorbent 5, the nitrogen oxide adsorbent 5 is placed in a reducing atmosphere. Further, the nitrogen oxide adsorbing material 5 is also placed in a temperature rising atmosphere by the heat of the first burned gas. Since the nitrogen oxide adsorbing material 5 is placed in a reducing atmosphere (further higher temperature atmosphere), the nitrogen oxide adsorbed on the nitrogen oxide adsorbing material 5 is desorbed from the nitrogen oxide adsorbing material 5. The desorbed nitrogen oxides are mixed with the first post-combustion gas and sent to the exhaust downstream side (second combustion region A2 side).

  In particular, the main regeneration operation is composed of a first stage with a large flow rate (first main regeneration operation) and a second stage with a small flow rate (second main regeneration operation). This is due to the following reason. If the flow rate is increased in the initial stage of the main regeneration operation, the desorption start time is advanced. Further, once desorption is started, desorption continues even if the flow rate is reduced thereafter. Therefore, the flow rate in the first stage is increased in order to advance the desorption start time, and the flow rate in the second stage is decreased so that the flow rate (energy consumption per unit time) can be reduced while maintaining the desorption reaction. Yes.

  The control device 10 operates the second combustion device 7 and the auxiliary air supply means 17 simultaneously with or after the operation of the first combustion device 6 in the regeneration operation. By the operation of the second combustion device 7, a mixed gas of fuel and air is generated in the second combustion regions A2 and A3. Air is further supplied to the third combustion region A3 by the auxiliary air supply means 17.

  Here, the mixed gas generated in the second combustion region A2 is referred to as a second mixed gas, and the mixed gas formed in the third combustion region A3 is referred to as a third mixed gas. Since more air is supplied to the third mixed gas than the second mixed gas, the excess air ratio of the third mixed gas is higher than the excess air ratio of the second mixed gas. Therefore, by appropriately setting the amount of fuel and air supplied by the second combustion device 7 and the amount of air supplied by the auxiliary air supply means 17, combustion is performed in the second combustion region A2 under an excess fuel condition. It is possible to generate a reaction and generate a combustion reaction under the excess air condition in the third combustion region A3.

  The first post-combustion gas from the first combustion region A1 reaches the second combustion region A2. Therefore, in the second combustion region A2, the second mixed gas and the first post-combustion gas are combusted to generate the second post-combustion gas. Here, the operation of the second combustion device 7 (the amount of fuel and air supplied) is controlled so that the combined gas of the second mixed gas and the first post-combustion gas causes excess fuel.

  The second post-combustion gas generated under the excessive fuel condition contains many unburned substances. For this reason, nitrogen oxides contained in the second post-combustion gas (nitrogen oxides desorbed from the nitrogen oxide adsorbent 5) are reduced by the unburned matter contained in the second post-combustion gas, and converted to nitrogen. Become. In this way, nitrogen oxides contained in the exhaust gas from the internal combustion engine are rendered harmless.

  The second post-combustion gas containing nitrogen and unburned substances is sent to the exhaust downstream side (third combustion region A3) by the gas flow generated by the air nozzles 61 and 71.

  In the third combustion region A3, the third mixed gas and the second post-combustion gas are combusted to generate the third post-combustion gas. Here, the operation of the second combustion device 7 (supply amount of fuel and air) and the operation of the auxiliary air supply means 17 (so that the combined gas of the third mixed gas and the second post-combustion gas becomes excess air) Air supply amount) is controlled.

  By burning the third mixed gas and the second post-combustion gas under excess air conditions, unburned substances (carbon monoxide and hydrocarbons) contained in the second post-combustion gas are oxidized. And the unburned material which the 1st combustion device 6 generated for reduction of nitrogen oxides is removed. The particulate matter is also oxidized and removed.

  The third post-combustion gas from which unburned substances have been removed is sent to the exhaust downstream side by the gas flow generated by the air nozzle 171 in addition to the gas flow generated by the air nozzles 61 and 71. Then, the third post-combustion gas is released into the atmosphere via the merged exhaust passage 110.

  In the present embodiment, by using the second combustion device 7 and the auxiliary air supply means 17, excessive fuel combustion is generated in the second combustion region A2, and excessive air combustion is generated in the third combustion region A3. . The configuration for simultaneously generating excess fuel combustion and excess air combustion is not limited to this configuration. For example, even with the configuration of the second combustion device 7 alone, it is possible to simultaneously generate excess fuel combustion and excess air combustion. In this case, by utilizing the fact that the portion near the fuel injection position is excessive fuel and the portion far from the fuel injection position is excessive air, excessive fuel combustion is generated in the second combustion region A2, and the third combustion region A3. Causes excessive air combustion.

  In the post-regeneration operation, the control device 10 operates the first combustion device 6 under an excess air condition as in the pre-regeneration operation. For this reason, when the first post-combustion gas passes through the nitrogen oxide adsorbing material 5, the reducing agent (hydrocarbon or carbon monoxide, which is unburned) adhering to the nitrogen oxide adsorbing material 5, Oxidized and removed. Here, the unburned material adheres to the nitrogen oxide adsorbing material 5 in the main regeneration operation prior to the post-regeneration operation, and the first post-combustion gas generated under the excessive fuel condition passes through the nitrogen oxide adsorbing material 5. Because. Further, the particulate matter captured by the nitrogen oxide adsorbing material 5 is oxidized and removed.

  The first post-combustion gas that has passed through the nitrogen oxide adsorbing material 5 is sent to the exhaust downstream side, and is released into the atmosphere via the merged exhaust passage 110.

  In the present embodiment, only the main regeneration operation activates the second combustion device 7 in the regeneration operation. In the main regeneration operation, for the purpose of reducing the nitrogen oxide desorbed from the nitrogen oxide adsorbing material 5 and removing the reducing agent (unburned material) used for the desorption of the nitrogen oxide, Actuated. Therefore, in the pre-regeneration operation and the post-regeneration operation, nitrogen oxide and reducing agent (unburned material) are not generated. Therefore, for the purpose of removing nitrogen oxide and reducing agent (unburned material), the second combustion device 7 is used. There is no need to activate it. However, the second combustion device 7 may be operated also in the pre-regeneration operation and the post-regeneration operation.

[Effect of this embodiment]
The exhaust gas purification device 1 of the present embodiment exhibits the following effects.

  Since the main regeneration operation is composed of a first stage with a large flow rate (first main regeneration operation) and a second stage with a small flow rate (second main regeneration operation), desorption is performed in the first stage with a large flow rate. The start time can be advanced, and the flow rate (energy consumption per unit time) can be reduced while maintaining the elimination reaction by the second step with a small flow rate. On the other hand, when the flow rate is constant, the desorption start timing is delayed if the flow rate is small, and if the flow rate is sufficient, the flow rate after the start of the desorption reaction is excessive in order to continue the desorption reaction. That is, the present configuration in which the flow rate is changed from large to small can reduce the execution time (desorption time) of the main regeneration operation or the total flow rate (energy consumption) as compared with the case where the flow rate is constant.

  Therefore, as the stage in the main regeneration operation progresses, the flow rate of the first mixed gas is decreased, thereby efficiently increasing the desorption amount of nitrogen oxide without increasing the energy consumption and the time required for desorption. it can. Further, since the temperature is raised in the initial stage of the main regeneration operation, the start of desorption can be accelerated.

  In the main regeneration operation, the excess air ratio λ of the first mixed gas is controlled in the range of 0.6 <λ <1.0, so that the nitrogen oxide can be effectively desorbed from the nitrogen oxide adsorbing material 5. .

  In the pre-regeneration operation, the excess air ratio λ of the first mixed gas is controlled in the range of λ> 1.0, so that the amount of particulate matter captured by the nitrogen oxide adsorbing material 5 can be reduced. Further, the temperature of the nitrogen oxide adsorbing material 5 can be raised prior to the main regeneration operation, and the efficiency of the main regeneration operation can be improved.

  In the post-regeneration operation, the excess air ratio λ of the first mixed gas is controlled in the range of λ> 1.0, so that the reducing agent adhering to the nitrogen oxide adsorbing material 5 (hydrocarbon which is unburned) And carbon monoxide) can be removed, and the amount of reducing agent discharged outside the apparatus when normal operation is performed can be reduced. In addition, the amount of particulate matter captured by the nitrogen oxide adsorbing material 5 can be reduced.

  The present invention can be applied to an apparatus for purifying exhaust gas from an internal combustion engine such as a diesel engine, a gas engine, a gasoline engine, or a gas turbine engine, or a combustion device such as an incinerator or a boiler.

It is the schematic of an exhaust-gas purification apparatus. It is a figure which shows the time table | surface of the normal driving | operation and regeneration driving | operation in each branch exhaust passage. It is a figure which shows the time change of the gas flow rate in a reproduction | regeneration driving | operation. It is the schematic of the conventional exhaust gas purification apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exhaust gas purification apparatus 2, 3 Branch exhaust passage 2a, 3a Exhaust inlet 2b, 3b Exhaust outlet 4 Shut-off valve 5 Nitrogen oxide adsorption material 6 1st combustion apparatus 7 2nd combustion apparatus 10 Control apparatus 61, 71, 151 Air nozzle (Part of air supply means)
62, 72 Fuel nozzle (part of fuel supply means)
63, 73 Spark plug (ignition device)
100 Engine side exhaust passage 100b Exhaust outlet

Claims (2)

A plurality of branch exhaust passages connected to an engine side exhaust passage of an internal combustion engine or combustion equipment;
An exhaust gas shut-off means that opens or closes the exhaust inlet of each branch exhaust passage to switch inflow and shut-off of exhaust gas from the engine-side exhaust passage to each branch exhaust passage;
A nitrogen oxide adsorbent that is provided in each branch exhaust passage, temporarily adsorbs nitrogen oxides in an excess air atmosphere, and desorbs the adsorbed nitrogen oxides in a temperature rising or reducing atmosphere;
Each of the branched exhaust passages is disposed upstream of the nitrogen oxide adsorbing material and includes an air supply means, a fuel supply means, and an ignition means, and supplies a first mixed gas in which fuel and air are mixed. A first combustion device for burning;
A second combustion device that is disposed on the exhaust downstream side of the nitrogen oxide adsorbent in each of the branch exhaust passages and includes an air supply means, a fuel supply means, and an ignition means;
In the control method of the exhaust gas purification device, comprising:
For each branch exhaust passage, there are normal operation and regeneration operation,
The normal operation is an operation in which exhaust gas flows into the branch exhaust passage where the normal operation is performed by switching the exhaust gas blocking means,
In the regeneration operation, the first combustion device and the second combustion device are operated in a state where the exhaust gas is prevented from flowing into the branch exhaust passage where the regeneration operation is performed by switching the exhaust gas blocking means. Driving
The regeneration operation consists of a pre-regeneration operation, a first main regeneration operation, a second main regeneration operation, and a post-regeneration operation, which are executed in order,
In the first main regeneration operation and the second main regeneration operation , the excess air ratio λ of the first mixed gas is controlled in a range of λ <1.0.
In the pre-regeneration operation and the post-regeneration operation, the excess air ratio λ of the first mixed gas is controlled in a range of λ> 1.0,
The flow rate of the first mixed gas decreases in the order of the first main regeneration operation, the pre-regeneration operation, the post-regeneration operation, and the second main regeneration operation.
A control method for an exhaust gas purifying apparatus. In the control method of the exhaust-gas purification apparatus of Claim 1,
In the first main regeneration operation and the second main regeneration operation , the excess air ratio λ of the first mixed gas is controlled in a range of 0.6 <λ <1.0.
Control method of exhaust gas purification device.

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